Handheld electronic device having a cover turnable 360 degrees relative to  a body thereof

ABSTRACT

A handheld electronic device ( 300 ) mainly comprises a cover ( 310 ), a main body ( 320 ), a monitor ( 328 ) mounted on the main body, a keyboard ( 318 ) mounted on the cover and a hinge structure ( 330 ) to which pivot portions ( 312 ), ( 322 ) of the cover and main body are hinged. The pivot portions have teeth ( 314 ), ( 324 ) on circumferential peripheries thereof. The teeth mesh with each other. The cover can rotate for 360 degrees relative to the main body thereby moving from a first position to a second position, wherein at the first position, the cover abuts against a top surface ( 326 ) of the main body, and at the second position, the cover abuts against a bottom surface of the main body. The trajectory of the cover during its rotation relative to the main body follows a predetermined path.

CROSS-REFERENCE TO RELATED APPLICATION

The present invention was first described in Disclosure DocumentRegistration 537,979 filed on Sep. 8, 2003 under 35 U.S.C. .sctn.122, 37C.F.R. .sctn.1.14 and MPEP .sctn. 1706. This application claims thebenefit of Taiwan application Serial No. 93210614, filed on Jul. 6,2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a handheld electronic device. Moreparticularly, the present invention relates to a handheld electronicdevice having a cover and a body; the cover can rotate 360 degreesrelative to the body.

2. Description of the Related Art

Handheld electronic device is now a widely adopted term referring tothose small and portable electronic devices such as mobile phones,pocket personal computers, electronic games, electronic dictionaries,personal digital assistants or portable personal computers. Becausehandheld electronic devices can be interconnected through wirelesscommunication systems or the Internet, it is a versatile and efficientpiece of high-tech mobile information processing equipment.

FIGS. 1A and 1B show a conventional flip-top handheld electronic deviceat closed and opened positions. The device has a flip cover 110 and amain body 120, which are hinged together through a hinge structure 130.The hinge structure 130 is a single pivot structure. Due to structuralinterference between the flip cover 110 and the main body 120, the flipcover 110 cannot be rotated 360° relative to the main body 120 to reston a bottom surface of the main body 120, which is desirable in someapplications, for example, when a user needs to use a stylus (not shown)to input information through a stress-sensitive touch screen (not shown)on the flip cover 110 of the device.

FIG. 2 is a perspective view of another conventional handheld electronicdevice. As shown in FIG. 2, the device has a main body 220 and a cover210. A screen 212 is provided on the cover 210 and a keyboard 222 isprovided on the body 220. The cover 210 is connected to the main body220 through a hinge structure including a first pivot 230 and a secondpivot 232. The first pivot 230 enables the cover 210 to rotate relativeto the main body 220 on a vertical plane, and the second pivot 232enables the cover 210 to rotate relative to the main body 220 on ahorizontal plane, whereby the cover 210 can be moved to rest on a topsurface (not labeled) of the main body 220 with the screen 212 facesupwardly. Although the hinge structure of FIG. 2 enables a user to inputinformation to the device through use of a stylus tapping on the screen212, this type of hinge structure enabling two-plane rotation iscomplicated and expensive to produce.

In U.S. Pat. No. 4,825,395, a two axis articulated hinge design forconnecting the two casings of an electronic computer is disclosed. Theadvantage of using the two-axis articulated hinge structure is thatstructural interference will not occur, and one of the casings can bedirectly rotated to rest on the other from a top surface to a bottomsurface thereof. However, one major disadvantage for this design is thatthere is no fixed relative position between the two casings except atthe two end positions in which the two casings rest on each other. Thehinge structure of another U.S. Pat. No. 5,898,600 also has similarproblem regarding the relative positioning between the casings.

The problem of not having a fixed relative position between the twocasings of a flip type handheld electronic device as in theaforementioned hinge designs can be explained with respect to FIGS. 2Athrough 2C. FIGS. 2A through 2C are side views of a conventionaltwo-axis handheld electronic device. As shown in FIGS. 2A through 2C, ahandheld electronic device 10 has a first casing 12, a second casing 14and a connecting plate 16 with two edges connected to hinge axes 18, 20of the first and the second casings 12, 14 respectively. When the secondcasing 14 is rotated to a vertical position relative to the first casing12, the connecting plate 16 can be disposed in a horizontal position(shown in FIG. 2A), a slant position (shown in FIG. 2B), a verticalposition (shown in FIG. 2C) or any position in-between. Since theorientation of the connecting plate 16 is quite arbitrary, the firstcasing 12 and the second casing 14 are not fixed relative to each other.Such an inability to fix the relative position between the two casings12, 14 at a position between the end positions is undesirable.

SUMMARY OF THE INVENTION

Accordingly, at least one objective of the present invention is toprovide a handheld electronic device having no structural interferencebetween its cover and main body so that the cover can rotate by an angleup to 360° relative to the main body, whereby the cover can rest oneither a top surface or a bottom face of the main body through a simplerotation of the cover relative to the main body.

At least a second objective of the present invention is to provide ahandheld electronic device having a secure and reliable relativepositioning between its cover and main body when the cover is rotated byan angle up to 360° relative to the main body.

To achieve these and other advantages and in accordance with the purposeof the invention, as embodied and broadly described herein, theinvention provides a handheld electronic device. The handheld electronicdevice mainly comprises a first casing, a second casing and a hingestructure. The first casing has a first pivot portion and the secondcasing has a second pivot portion. Each of the first and the secondpivot portion has a plurality of protruding teeth. The teeth of thefirst pivot portion mesh with the teeth of the second pivot portion. Thehinge structure has two axle rods around which the first and secondpivot portions rotate, respectively. The two axle rods are securelyfastened to two axle caps respectively at two opposite ends of the axlerods. Through this design, the first casing can rotate by an angle up to360° relative to the second casing and a relative position between thetwo casings during the rotation can be deterministic.

The present invention also provides an alternative handheld electronicdevice comprising a first casing, a second casing, a hinge structure anda lever wherein the hinge structure and the lever connect the first andsecond casings together. The first casing can rotate relative to thesecond casing. The first casing and the second casing have a first pivotportion and a second pivot portion, respectively. The hinge structurehas first and second pivots which are respectively connected to thefirst and second pivot portions of the first and second casings. Thelever has a first end and a second end that are fastened to the firstcasing and the second casing, respectively. The first end and the secondend of the lever are located at different sides of a line joining axesof the first and the second pivot portions.

In the present embodiment, assuming that a distance between the firstend of the lever and the axis of the first pivot portion is X and adistance between the second end of the lever and the axis of the secondpivot portion is Y, a length of the lever between the first and secondends is S and a distance between the axis of the first pivot portion andthe axis of the second pivot portion is R. The relationship between X,Y, S and R is S>R, S+Y=R+X and S²=R²+(X+y)². By such geometric relationbetween the first and second casings, the hinge structure and the lever,the first casing can rotate smoothly up to an angle of 360° relative tothe second casing without any interference between the two casings, andduring the rotation the relative position between the two casings can bedeterministic.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, and are intended toprovide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIGS. 1A and 1B show a conventional handheld electronic device with aflip cover at closed and opened positions relative to a main bodythereof.

FIG. 2 is a perspective view of another conventional handheld electronicdevice.

FIGS. 2A through 2C are side views of a conventional two-axis handheldelectronic device.

FIG. 3 is a perspective view of a handheld electronic device accordingto a first preferred embodiment of the present invention at a closedposition.

FIG. 3A is a magnified, cross-sectional view of a portion of thehandheld electronic device of FIG. 3, showing details of a hingeconnection between a cover and a main body of the handheld electronicdevice.

FIG. 3B is a magnified, top view of two axle rods and two rod caps ofthe handheld electronic device of FIG. 3.

FIGS. 4, 5, 6 and 7 are perspective views respectively showing the coverof the handheld electronic device of FIG. 3 being rotated by an angle of90°, 180°, 270° and 360° relative to the main body of the device.

FIGS. 4A, 5A, 6A and 7A are views similar that of FIG. 3A, respectivelyshowing details of the hinge connection of FIGS. 4, 5, 6 and 7.

FIG. 8 is a perspective view of a handheld electronic device accordingto a second preferred embodiment of the present invention.

FIG. 8A is an exploded view of the handheld electronic device shown inFIG. 8.

FIG. 8B is a diagram showing the movement of a hinge structure of thehandheld electronic device shown in FIG. 8A.

FIG. 8C is a side view of the handheld electronic device shown in FIG.8.

FIG. 8D is a diagram showing a geometric relationship between the hingestructure and a lever of the handheld electronic device of FIG. 8C.

FIGS. 9, 10, 11 and 12 are side views showing a cover of the handheldelectronic device in FIG. 8 being rotated by an angle respectively of90°, 180°, 270° and 360° relative to a main body thereof.

FIG. 10A is a diagram showing a geometric relationship between the hingestructure and the lever of the handheld electronic device of FIG. 10.

FIG. 13 is a perspective view showing a handheld electronic deviceaccording to a third preferred embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the present preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numbers areused in the drawings and the description to refer to the same or likeparts.

FIG. 3 is a perspective view of a handheld electronic device 300according to a first preferred embodiment of the present invention. FIG.4 shows a cover 310 of the handheld electronic device 300 of FIG. 3being rotated by 90° relative to a main body 320 thereof. FIG. 5 showsthe cover 310 being rotated by 180°. FIG. 6 shows the cover 310 beingrotated by 270°. FIG. 7 shows the cover 310 being rotated by 360°.

As shown in FIG. 3, the handheld electronic device 300 mainly comprisesthe cover 310, the main body 320 and a hinge structure 330. FIG. 3A is amagnified, cross-sectional view of the hinge structure 330 shown in FIG.3. In the present embodiment, the cover 310 and the main body 320 have afirst pivot portion 312 and a second pivot portion 322, respectively.Each of the first and the second pivot portions 312, 322 has a pluralityof protruding teeth 314, 324 on a circumferential periphery thereof,which has a profile generally of a semicircle. The teeth 314, 324 meshwith each other.

The hinge structure 330 in FIG. 3A comprises a first axle bushing 334and a second axle bushing 336 respectively secured to the first pivotportion 312 and the second pivot portion 322. Also referring to FIG. 3B,two axle rods 337, 338 each have two opposite ends respectively securedto two axle caps 332, 333. The axle rods 337, 338 respectively extend inthe axle bushings 334, 336 so that the first and second pivot portions312, 314 can rotate respectively about the axle rods 337, 338. The pivotportions 312, 314 are lengthwise sandwiched between the axle caps 332,333 so that lengthwise relative movement between the first and secondpivot portions 312, 314 is restrained.

In the following please also refer to FIGS. 3˜7A to understand therelative movement between the cover 310 and the main body 320 atdifferent positions. As shown in FIGS. 3 and 3A, when the cover 310covers a top surface 326 of the body 320 on which a monitor 328 (FIG.4A) is disposed, the protruding teeth 314, 324 on the first pivotportion 312 and the second pivot portion 322 which are located proximateto the surface 326 mesh with each other. As shown in FIGS. 4 and 4A, toopen the cover 310 for 90 degrees relative to the main body 320, theaxle rod 337 rotates for 45 degrees relative to the axle rod 338. Atthis position, the monitor 328 on the main body 320 and a keyboard 318on a bottom surface 316 of the cover 310 are exposed. The monitor 328and the keyboard 318 face each other and are oriented perpendicularly toeach other so that a user can easily input information into the device300 through typing the keyboard 318, and check the correctness of theinput information through looking at the monitor 328 when the cover 310is oriented horizontally and the main body 320 is oriented vertically.As shown in FIGS. 5 and 5A, to open the cover 310 for 180 degreesrelative to the main body 320, the axle rod 337 rotates for 90 degreesrelative to the axle rod 338. At this position, the cover 310 and themain body 320 extend substantially on a common plane. As shown in FIGS.6 and 6A, to open the cover 310 for 270 degrees relative to the mainbody 320, the axle rod 337 rotates relative to the axle rod 338 for 135degrees. Finally, as shown in FIGS. 7 and 7A, to open the cover 310 for360 degrees relative to the main body 320, the axle rod 337 rotatesrelative to the axle rod 338 for 180 degrees. At this position, thecover 310 abuts against a bottom surface (not labeled) of the main body320, and the user can easily input information to the device 300 throughuse of a stylus (not shown) tapping on the monitor 328, which in thepreferred embodiment is a touch screen. Furthermore, at this position,the user can easily use the device 300 as a wireless Internet browser ora wireless PDA phone. In a word, at the configuration of FIG. 7, thedevice 300 can be used as a wireless PDA with a structure of a singleslate. To close the device, the user only needs to move the cover 310relative to the main body 320 in a reverse direction.

It should be noted that the cover 310 can be rotated further from theflat-out configuration shown in FIG. 5 to the configuration in FIG. 7without any structural interference between the cover 310 and the mainbody 320. Consequently, the cover 310 is free to rotate 360° from theclosed position shown in FIG. 3 to the one in FIG. 7 to enable the mainbody 320 to be located beneath the main body 320. In the configurationof FIG. 7, the keyboard 318 on the cover 310 and the monitor 328 on thebody 320 face opposite directions.

Accordingly, the first embodiment of the present invention utilizes axlecaps 322, 334 and axle rods 337, 338 to connect the cover 310 and mainbody 310, 320 together. By meshing the protruding teeth 314, 324distributed on the circumferential peripheries of the first and thesecond pivot portions 312, 322, the cover 310 is free to rotate by anangle up to 360 degrees relative to the main body 320. Furthermore, thecover 310 follows a predetermined trajectory during its rotationrelative to the main body 320. In other words, in the present invention,the relative position between the main body 320 and the cover 310 isalways ascertained during the relative rotation there between; thus, thepresent invention can resolve the problem of the prior art device.

FIG. 8 is a perspective view of a handheld electronic device 400according to a second preferred embodiment of the present invention.FIG. 8A is an exploded view of the handheld electronic device 400 ofFIG. 8. FIG. 8B is a diagram showing a movement of a hinge structure 430of the handheld electronic device 400 during a rotation of a cover 410relative to a main body 420 thereof. FIG. 8C is a side view of thehandheld electronic device 400 at a closed position. FIG. 8D shows ageometric relationship between a lever 440 and the hinge structure 430of the handheld electronic device 400 of FIG. 8C.

As shown in FIG. 8, the handheld electronic device 400 is a wirelesspersonal digital assistant. The handheld electronic device 400 mainlycomprises the cover 410, the main body 420, the hinge structure 430 andthe lever 440. In the present embodiment, the cover 410 and the mainbody 420 have a first pivot portion 412 and a second pivot portion 422,respectively. The first and the second pivot portions 412, 422 arehinged to the hinged structure 430. Although in this embodiment thecover 410 has a thickness smaller than that of the main body 420, it isunderstood that the cover 410 can have a thickness equal to that of themain body 420. In contrast to this embodiment, in the first embodimentof FIG. 3, the cover 310 of the handheld electronic device 300 must havea thickness equal to that of the main body 320. The main body 420 can beequipped with a keyboard (not shown), while the cover 410 can beequipped with a display screen (not shown).

As shown in FIG. 8B, the hinge structure 430 has a dual-axis hingedesign with one axis hinged to an axis A of the first pivot portion 412of the cover 410 and the other axis hinged to an axis B of the secondpivot portion 422 of the main body 420. One major advantage of thisarrangement is that the cover 410 is able to rotate up to 360° relativeto the main body 420 through the hinge structure 430 without anystructural interference between the cover 410 and the main body 420.However, such connection cannot achieve the object of the presentinvention: to conform to a deterministic relative position of the cover410 to the main body 420 during the rotation of the cover 410. Toachieve the object, the lever 440 is introduced to work in tandem withthe hinge structure 430 so that a certain relative position is providedand the connection structure is strengthened. As shown in FIG. 8, thelever 440 has a first end 442 and a second end 444. The first end 442 ishinged to the first casing 410 and the second casing 444 is hinged tothe second casing 420. Furthermore, the first end 442 and the second end444 are located on different sides of an imaginary line joining the axisA of the first pivot portion 412 and the axis B of the second pivotportion 422.

According to the present invention, the first and second ends 442, 444of the lever 440 are hinged to points of the cover 410 and main body 420other than the axes A, B of the first and the second pivot portions 412,422 thereof. As shown in FIGS. 8C, 8D, assuming a distance between thefirst end 442 of the lever 440 and the axis A of the first pivot portion412 is X, a distance between the second end 444 of the lever 440 and theaxis B of the second pivot portion 420 is Y. The lever 440 has a lengthof S between the two ends 442, 444 thereof and the hinge structure 430has a length of R between the two axes A, B thereof. Then, the values ofX, Y, S and R must satisfy the following equations in order for thecover 410 to move smoothly and reliably along a predetermined pathrelative to the main body 420. The equations are:

S ² =R ²+(X+Y)²  (as shown in FIG. 8D);

S+Y=R+X  (as shown in FIG. 10A).

FIG. 9 is a side view showing the cover 410 of the handheld electronicdevice 400 in FIG. 8 being rotated by an angle of 90° relative to themain body 420. FIG. 10 is a side view showing the cover 410 of thehandheld electronic device 400 in FIG. 8 being rotated by an angle of180° relative to the main body 420. FIG. 11 is a side view showing thecover 410 of the handheld electronic device 400 in FIG. 8 being rotatedby an angle of 270° relative to the main body 420. FIG. 12 is a sideview showing the cover 410 of the handheld electronic device 400 in FIG.8 being rotated by an angle of 360° relative to the main body 420.

In FIGS. 8 and 8C, when the cover 410 flips over a top surface 424 ofthe main body 420, the geometric relationship is governed by the firstequation, namely, S²=R²+(X+Y)². In the present embodiment, the length Sis greater than the length R and the distance X is greater than thedistance Y. When the first casing 410 shown in FIG. 8 rotates 90° toreach the position shown in FIG. 9, the angle between the cover 410 andthe main body 420 is 90°. Thereafter, when the first casing 410 shown inFIG. 9 rotates another 90° to reach the position shown in FIG. 10, thesecond equation, namely, S+Y=R+X , must be satisfied. At this position,the angle between the cover 410 and the main body 420 is 180°. In FIGS.11 and 12, the cover 410 rotates respectively 270° relative to the mainbody 420 and 360° relative to the main body 420. At the position of FIG.12, the cover 410 abuts a bottom surface of the main body 420.

Therefore, if the geometry relationship of the lever 440 and the hingestructure 430 and their connections with the cover 410 and main body 420satisfies the two aforementioned equations, the cover 410 can rotate upto 360° relative to the main body 420 and the position of the cover 410relative to the main body 420 can be always ascertained throughout therotation of the cover 410.

In the following table, different examples of values of R, X, Y and Sthat meet the two aforementioned equations are listed. With thesevalues, a person skilled in the art can readily construct the handheldelectronic device 400 in accordance with the second embodiment of thepresent invention with a variety of sizes.

R X Y S R + X S + Y 2.000 1.000 0.500 2.500 3.000 3.000 2.000 2.0000.667 3.333 4.000 4.000 2.000 3.000 0.750 4.250 5.000 5.000 2.000 4.0000.800 5.200 6.000 6.000 2.000 5.000 0.833 6.167 7.000 7.000 2.000 6.0000.857 7.143 8.000 8.000 2.000 7.000 0.875 8.125 9.000 9.000 2.000 8.0000.889 9.111 10.000 10.000 3.000 1.000 0.600 3.400 4.000 4.000 3.0002.000 0.857 4.143 5.000 5.000 3.000 3.000 1.000 5.000 6.000 6.000 3.0004.000 1.091 5.909 7.000 7.000 3.000 5.000 1.154 6.846 8.000 8.000 3.0006.000 1.200 7.800 9.000 9.000 3.000 7.000 1.235 8.765 10.000 10.0003.000 8.000 1.263 9.737 11.000 11.000 3.000 9.000 1.286 10.714 12.00012.000 4.000 1.000 0.667 4.333 5.000 5.000 4.000 2.000 1.000 5.000 6.0006.000 4.000 3.000 1.200 5.800 7.000 7.000 4.000 4.000 1.333 6.667 8.0008.000 4.000 5.000 1.429 7.571 9.000 9.000 4.000 6.000 1.500 8.500 10.00010.000 4.000 7.000 1.556 9.444 11.000 11.000 4.000 8.000 1.600 10.40012.000 12.000 4.000 9.000 1.636 11.364 13.000 13.000 4.000 10.000 1.66712.333 140.000 14.000 4.000 11.000 1.692 13.308 15.000 15.000 4.00012.000 1.714 14.286 16.000 16.000 5.000 1.000 0.714 5.286 6.000 6.0005.000 2.000 1.111 5.899 7.000 7.000 5.000 3.000 1.364 6.636 8.000 8.0005.000 4.000 1.538 7.462 9.000 9.000 5.000 5.000 1.667 8.333 10.00010.000 5.000 6.000 1.765 9.235 11.000 11.000 5.000 7.000 1.842 10.15812.000 12.000 5.000 8.000 1.905 11.095 13.000 13.000 5.000 9.000 1.95712.043 14.000 14.000 5.000 10.000 2.000 13.000 15.000 15.000 5.00011.000 2.037 13.963 16.000 16.000 5.000 12.000 2.069 14.931 17.00017.000 5.000 13.000 2.097 15.903 18.000 18.000 5.000 14.000 2.121 16.87919.000 19.000 5.000 15.000 2.143 17.857 20.000 20.000

In the aforementioned table, the values of the R, X, Y, S of each roware set to express the dimensional proportions of theses dimensions inthe handheld electronic device 400. There are three rows in the table inwhich the dimensional proportions of these dimensions are integrals,i.e., 3:3:1:5, 4:2:1:5 and 5:10:2:13 for R: X: Y: Z, by which the personcan easily construct the handheld electronic device 400 which canoperate perfectly smoothly. For those rows having values not beingintegral, a round off to the nearest hundredth thereof can be used. Forexample, the R: X: Y: Z of the last row can be rounded off to be5:15:2.14:17.86. Due to operation tolerance, such round off will not tooadversely affect the smoothness of the operation of the device 400.

In the present embodiment, the display screen (not shown) and thekeyboard (not shown) are disposed on the cover 410 and the main body420, respectively. When the cover 410 rotates 360° relative to the mainbody 420 to abut against the bottom surface of the main body 420 asshown in FIG. 12, the display screen and the keyboard face oppositedirections. At this position, the user can easily input information tothe device 400 through use of a stylus (not shown) tapping on thedisplay screen, which in the preferred embodiment is a touch screen.Furthermore, at this position, the user can easily use the device 400 asa wireless Internet browser or a wireless PDA phone.

In this embodiment of the present invention, although only one lever 440is shown connected to one side of the device 400, it can be easilyunderstood by persons skilled in the art that a second lever can be usedto secure the other side of the device 400 to enhance the structuralintegrality and robustness of the device 400. FIG. 13 is a perspectiveview showing a handheld electronic device 500 in accordance with a thirdembodiment of the present invention, which differs from the secondembodiment only regarding the disposition of the level. In the thirdembodiment, the lever (not shown) is no longer placed on a side of thehandheld electronic device, but is placed in a slit 502 defined in amiddle of a front end portion of the handheld electronic device 500.Like the second embodiment, the device 500 has a hinge structure 530connecting with a first pivot portion of a cover 510 and a second pivotportion of a main body 520 of the device 500, respectively. Furthermore,the lever has two ends pivotably connected to the cover 510 and the mainbody 520 of the device 500, respectively. By such design, the lever ishidden in the device 500, thereby enhancing the aesthetic appeal of thedevice 500. The operation of the device 500 is the same as that of thedevice 400 of the second embodiment.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncovers modifications and variations of this invention provided they fallwithin the scope of the following claims and their equivalents.

1-9. (canceled)
 10. A handheld electronic device, comprising: a firstcasing having a first pivot portion; a second casing having a secondpivot portion; a hinge structure to which the first and the second pivotportions are hinged at a first axis and a second axis, respectively; anda lever having a first end and a second end, wherein the first endhinges to the first casing and the second end hinges to the secondcasing, and the first end and the second end are respectively located atdifferent sides of a line joining the first and second axes.
 11. Thehandheld electronic device of claim 10, wherein a distance between thefirst end of the lever and the first axis is X, a distance between thesecond end of the lever and the second axis is Y, a length of the leverbetween the two ends is S and a distance between the first and secondaxes is R, and values of X, Y, R and S substantially satisfy equationsS+Y=R+X and S²=R²+(X+Y)².
 12. The handheld electronic device of claim11, wherein the first casing has a monitor and the second casing has akeyboard disposed thereon. 13-24. (canceled)